Telephone system



Oci- 18, 1932- w. H. MATTHIES 1,882,851

TELEPHONE SYSTEM Filed Oct. l5, 1931 /NVENTOR W H. MA 7TH/E 5 Afro/mfrPatented Oct. 18, 1932 Unirse stares earner orties WILLIAM I-I.MATTI-HES, OF HACKENSAGK, NEEV JERSEY, ASSGNOR 'EJO BELL TLPHONELABORATORIES, INCORPORATED, OF NEW YORK, N. Y., A. CORPORATION O F NEWYORK TELEPHONE SYSTEM Application filed October 15, 1931. Serial No.568,927.

This invention relates to automatic telephone systems in which switchingapparatus is controlled to establish connections under the control of asubscribers impulse dial.

The invention has been disclosed as applied to the impulse receivingcircuit of a common register sender in Which registers are providedwhich are successively set in response to series of impulses dialed by acalling subscriber, such registers being instrumental in controlling thesetting of tne sel ctor switches to establish a telephone connectionfrom the call ing' subscribers line to the line Whose designation thecalling subscriber has caused to be registered on such registers.Obviously, the invention is also applicable to selector switch circuitsof the types Which are set directly by dia-led impulses rather thanthrough the intervention of a common sender.

Since a common sender may be taken into service by any one of a largenumber of subscribers lines7 it will be apparent that the dialing loopswhich may be established between the subscribers subst-ations and theimpulse responsive relay of the sender vT'ill vary considerably inlength and consequently in resistance. An impulse responsive relay whichWill operate satisfactorily over long loops of relatively highresistance, that is, release quickly each time the loop circuit isopened at the contacts of the subscribers dial, Will not operate as Wellover short loops of rela-tive low resistance, since with the lowerresistance, the relay will receive more current and its magnet core willbecome saturated to a. point which will render the rela-y sluggish torelease on circuit openings. @n the other hand an impulse relay whichwill operate satisfactorily over short loops of relatively loWresistance, will not operate as Well over long loops of relatively highresistance, since with the higher resist-ance the relay will not receivesuiiicient operating current between loop openings to properly saturateits magnet core and Will thus release too quickly. To render the`innrulse relay operable under such Wide operating conditions requires avery careful eesign and adjustment of the relay. It is therefore theobject of the present invention to obviate the aforementioneddifficulties by providing for the automa-tic Aadjustment of theresponsiveness of the impulse relay so that when an impulsing loop isestablished thereto of less than average resistance, the impulse relayis rendered less sensitive than when an impulsing loop of more thanaverage resistance is established. Thereby the impulse relay performsmore uniformly regardless of the resistance of the connected impulsingloop.

In accordance with the present invention this object may be attained inseveral Ways. In one embodiment of the invention a normally shuntedresistance and the opera-ting Winding of a marginally adjusted relay areconnected in series with the Winding of the impulse responsive relay inone leg of the impulsing loop. The shunt of the seriesresistancenormallyextends through contactsof the marginal relay. Shoulda line be connected to complete an impulsing loop of more `than averagelength through the Winding of the impulsing relay, the resistance ofsuch loop Will be high enough to prevent the operation of the seriallyconnected marginal relay. Should however, a. shorter loop be establishedof less than average length and consequently of lower resistance. thecurrent flowing thereover will be of sufficient strength to operate boththe impulse responsive relay andthe marginal relay. The marginal relayupon operating Will first establish a locking circuit for itself andWill then remove the shunt Afrom the series resistance therebyincreasing the resistance of the loop. By this means the resistance ofshort loops is increased to Ysubstantially the resistance of the longerloops and the impulse responsive relay is therefore always operated overloops having a smaller variation in resistance.

lf a. closer adjustment of loop resistance is found to be desirable, aplurality of resist.- ances and differently margined relays may beemployed in series with the impulse responsive relay, the margins ofsuch relays being so selected that the shorter the connecting impulsingloop is, the more compensating resistance Will be added in series withthe impulse responsive relay. Y

In accordance with a furtherembodiment CTL of the invention, the impulseresponsive relay may be normally biased by a dii'erentifl windingconnected into a biasing circuit through a resistance, and the marginalrelay connected in series with the operating winding of the impulserelay may be arranger when it operates over a low resistance impulsingloop to short circuit the resistance, thereby increasing the bias of theimpulse relay. Thus, when the impulse relay is connected into a. longiinpulsing loop, it is less biased than when it is connected into ashort loop.

For a more complete understanding` orn the invention reference may behad to the rollovfing details description talren in connection with theaccompanying drawing in which Fig. 1 shows diagrammatically asubscribers line, a line finder-district selector trunl; circuit andsuch portions of a common sender as are necessary to disclose theinvention;

Fig. 2 shows a modification of the invention by means of which a finercompensation of resistance in the dialing loop is attained; and

Fig. 3 shows a further embodiment oi the invention.

Referring to Fig. 1 of the drawing, a subscribers substation of anautomatic telephone system is disclosed at 100 having `the usual impulsedial 111. In response to the removal of the receiver at the substation100 for initiating a call, the calling line becomes eX- tended by linefinder 101 to the trunlr circuit 102 terminating in the districtselector 103 and by the usual link circuit, not shown, to the commonsender disclosed in the dot and dash rect-angle 104. Following theconnection of the calling substation 100 with the sender 104 animpulsing loop is established from battery through the impulse responsivrelay 105, the left winding of marginal relay 106, the left normalcontact of rela-y 106, conductor 107, the upper contacts ol" cam 106,brush 109 and terminal 110 of line finder 101 over the substation loopthrough the dial 111, terminal 112 and brush 118 of the line finder 101,lower contacts of cam 1111-, conductor 115 to ground through the windingot coil 116. Impulse responsive relay 105 operates over this circuit andcloses a circuit lor the slow-to-release relay 117 in the usual manner.

It will iirst be assumed that the substation 100 is connected over along line loop orn high resistance with the sender 104 and thatconsequently the marginal relay 106 does not receive suflicient currentto operate. Resistance 118, therefore, remains shunted at the leftContact ot relay 106 and relay 105 receives the maximum possibleoperating current. Upon the operation and release of the dial 111 theimpulse loop is interrupted in the usual manner to thereby cause theimpulse responsive relay to release and operate.

W hen the relay 105 releases upon the initial opening of its circuit, acircuit is established tor relay 119 which in turn closes the circuit ofrelay `120. Relay 120 operates and locks to od-normal ground and closesa shunt around the left winding of relay 106 to remove its impedanceJlfrom the impulsing loop. In view of the fact that the resistance of along loop may be high enough to prevent the impulse relay from receivinga suilieiently high enough saturation, a branch of the impulsing loop isalso extended from conductor 107 through condenser 121, resistance 122,back contact of relay 106 to off-normal ground for the purpose ofshuntinO the winding oi the impulse relay 105 when connected to long,high resistance loops thereby slowing up the release of the impulseresponsive relay 105.

Should the sender become connected to a subscribers line over a shortloop having low resistance, marginal relay 106 will become energized aswell as impulse relay 105. Relay 106 upon operating tiret operates itsright armature to close a locking circuit through its right winding'from off-normal ground and to disconnect the branch ol' the impulsingloop through condenser 121 and resistance 122. Thereafter relay 106opens its left contacts to remove the shunt from resistance 118.Resistance 118 is now included in the impulsing loop thereby increasingthe resistance of the loop to a point more nearly commensurate with theresistance of the longest loops.

ln 2 a modification of the invention is disclosed similar to Fig. 1except that an additional marginal relay 123 and an additionalresistance 124 are provided. The marginal relays 106l and 123 haveditl'erent operating margins. TWhen the sender becomes connected t0 asubscribers substation over a long line the current flowing through theoperating windings of relays 106 and 123 is not sulicient to operateeither of them. lf a line oi medium length is connected, relay 106 willoperate but relay 123 will not and therefore resistance 118 is includedin the impulsing loop. If a short line is connected both marginal relays106 and 128 will operate thereby including both resistances 118 and 124in the impulsing loop. Thus compensation is made for lines of threeaverage lengths. It will be obvious that a closer compensation might beobtained through the use of additional marginal relays and seriallyconnected resistance units. rlhe impedance of relays 106 and 123 may beremoved through the operation ol relay 120 as described in connectionwith Fig. 1.

ln accordance with the modification disclosed in Fig. 3 the impulsingloop at the sender includes the operating winding ot a marginal relay106 and the operating winding oi' impulse responsive relay 105. heimpulse responsive relay 105 is provided with a biasing windingconnected in circuit with a resistance 125. rllhe two windings of relay105 are dierent-ially wound so that iii) L circuits ol lower resistanceviliei ing winding is connected in circuit with resista -ce 125 it isnot biased to such an the* extent as 'to prevent it from respondingquiclly to dialed impulses. When the sender is seized over a short loopoic low resistance relay 106 operates and locks to oli-normal ground andat its left contact shunts the resistance 125 thereby increasing thecurrent i'iowing through the left biasing winding of relay 105. Relay105 is now more heavily biased and will not become over-saturated by thestronger current flowing over the short line loop. li" desired a shuntpath through a condenser and resistance such as is disclosed in n ig. 1could be employed controllable over a a ci; Contact of marginal relay106.

is previously stated the inventio., is not to be construed as limited inits application to the impulsing circuit of central ofiice senders sinceitis equally applicable to the impulse responsive circuit of switches ofthe tyl e vvhicl respond directly to impulse dialed by callin isubscribers.

What is claimed is 1. ln a signaling system, a responsive dev'ce, meansc; establishing operating circuits of diiierent resistance to saidresnonsive device, means operative over said circuits :for determiningwhether a particular circuit is of relatively high or low resistance,and means controlled by said means for rendering said responsive deviceless responsive it said circuit is found to be of 10W resistance.

2. ln a signaling system, a responsiveA device, means for establishinoperatin circuits of dilterent resistance to sain responsive device, andmeans independent of said responsive device operative over said circuitsfor automatically che.. resistance of d circuits whereby the resis `ceof all of l said circuits is more nearly equa.. ln a signaling; sv in, ar vice, means igor establishio cuits to said device, the csistai of saidcircuits being` lower th i adding resistance thereto whereby theresistance ci il of said circuits is more nearly equalized.

4. ln a signaling svstem, a responsive device, means for establisliicuits to said device, the r ci said circuits bein si' operating?,l cir-Y of certain 'lower (e connected in series with said responsive defioperative only ov r the circuits or stance 'for adding i'csistaceto saidra'lit of substatlons a responsive devicev means for establishing anoperatingcircuit t said device from any ol said substations,saicioperating circuits having diierent resistance in accordance with 'thcdistance of said substations from said devi e, means independent or saidresponsive device operative only over such circuits as have relativelylow resistance for adding resistance thereto whereby said responsivedevice is always operable over circuits of more nearly equal resistance.n

G. In telephone exchange system, a plurality of substations, aresponsive device, means lor establishinel an operating circuit'to saiddevice from any of said substations, said operating circuit-s havingdifferent resistance in accordance with the distance of said substationsfrom said device,and a marginal relay associated scries with saidresponsive device andoperative only over 'the circuits of relatively lowresistance for adding resistance thereto whereby said responsive deviceis always operable over Lcircuits of more `nearly equal resistance.

7. In a telephone exchange system, a plurality of calling linesubstations, each having an impulse dial, an impulse vresponsive relaycommon thereto,Y means for establishing an operating circuit to saidrelay from any of said substations, said operating circuits havingdillerent resistance in accordance with the distance of said substationfrom said relay, and marginally adjusted mea-ns associated in serieswith said relay and operative only over the circ -its of relatively lowresistance for adding resistance thereto whereby said relay ance withthe distance or" said substations from said relay, and a marginal relayassociated in series with said relay and operable only over the circuitsof relatively low resistance for adding resistance thereto whereby saidimpulse relay is always responsive to dialed impulses over circuits ofmore nearly equal resistance.

0. In a signaling system, a responsive device, means itor establishingoperating circuits to said device, the resistance of certain or" saidcircuits being lower than the vresistance of other oi said circuits, anormally shunted resistance, and a marginal relay connected in serieswith said responsive device, said marginal relay operative only over theVEl() ing an operating circuit to said relay from any orp saidsubstations, said operating cir' cuits having different resistances inaccordance with the distance of said substations from said relay, anormally shunted resistance and a marginal relay connected in serieswith said impulse relay, said marginal relay operable only over thecircuits or relatively low resistance, contacts controlled by theoperation of said marginal relay for removing the shunt from saidresistance whereby the resistance or" all of said circuits is morenearly equa-lized.

ll. In a signaling system, a responsive relay, means for establishingoperating circuits to said relay, the resistance of certain of saidcircuits being lower than the resistance of other of said circuits,means normally in shunt of said responsive relay Jfor rendering itsluggish to release, and means operative only over the circuits or"lower resistance for removing said shunt.

l2. In a signaling system, a responsive relay, mea-ns for establishingoperating circuits to said relay, the resistance of certain of saidcircuits being lower than the resist-v ance of other of said circuits, acircuit oomprising a condenser and resistance normally in shunt of theWinding of said relay, and means operative only over the circuits oflower resistance for opening said shunt circuit.

13. In a signaling system, a responsive relay, means for establishingoperating circuits to said relay, the resistance of certain of saidcircuits being loiver than the resistance of other of said circuits,acircuit comprising a condenser and resistance normally in shunt oi"-the Winding oi` said relay, and means operative only over the circuitsof lower resistance for opening said shunt and for thereafter addingresistance to the operating circuit or" said relay.

In a telephone exchange system, a plurality of calling line substations,each having an impulse dial, an impulse responsive relay common thereto,means for establishing an operating circuit to said relay from any ofsaid substations, said operating oircuits having different resistancesin accordance with the distance of said substations from said relay, acircuit comprising acondenser and resistance normally in shunt of theWinding of said relay, a normally shunted resistance and a marginalrelay connected in series With said impulse relay, said marmy name this13th day of October, 1981.

WILLIAM H. MATTIIIES.

